Safety arming device for explosive missiles



Nov. 15, 1960 H. RAECH, JR., ETAL 2,960,037

SAFETY ARMING DEVICE FOR EXPLOSIVE MISSILES Filed Jan. 23. 1952 2Sheets-s 1 ill INVENTOR.

71 HARRY RAECH EDWARDP; Mm E Jail aw BY $1; ,5: f

TORNEYS:

Nov. 15, 1960 H. RAECH, JR., ETAL 2,950,037

SAFETY ARMING DEVICE FOR EXPLOSIVE MISSILES Filed Jan. 23. 1952 2Sheets-Sheet 2 INVENTOR. 5/2 HARRY RAECH JR. 21 EDWARD e McARDLEev/imwzlamlaw W fr JL ATTORNEYS- United States Patent O SAFETY ARMINGDEVICE FOR EXPLOSIVE MISSILES Harry Raech, Jr., Cleveland, Ohio, andEdward P. Mc-

Ardle, Philadelphia, Pa., assignors to the United States of America asrepresented by the Secretary of the y Filed Jan. 23, 1952, Ser. No.267,898

7 2 Claims. (Cl. 102-76) (Granted under Title 35, US. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government for governmental purposes without the payment of anyroyalty thereon.

Our invention pertains broadly to ammunition and explosive devices. Inparticular, it has reference to arming mechanisms incorporated inconventional artillery explosive projectiles, and in the war heads ofexplosive rockets such as those projected from the well-known bazooka,to render the projectiles and the war heads incapable of explosion untilafter they have been fired and have traveled a predetermined distancefrom the gun.

In the past, it was common practice to have such arming mechanismsdepend for their action upon the operation of a built-in, clock-likegear train mechanism driven by spring action, or by centrifugal forcegenerated as a result of causing the projectile to spin in its flight.In many cases, the spring action or the centrifugal force relied, inturn, upon one or more shear pins or upon bore riding pins.

Gear train mechanisms of the size used in arming devices, whether drivenby spring action or centrifugal force, were inherently delicate innature and liable to malfunctioning for manifest reasons; In addition,they were expensive to manufacture and assemble and, when completed,they required careful handling to preserve their workability. Thisrequirement placed an unnecessary, and sometimes impossible, task uponthose responsible for their handling. Many times, too, it has been foundthat a gear train mechanism, thought to be in good working order, wouldfail to operate when subjected to the severe shock created at the timeof firing the missile.

As those skilled in the art know, the use of arming devices whoseactuation depended upon centrifugal force was limited to operation withguns having the use of a rifled bore. Recently, there has been anincreased need for the use of smooth bore (i.e., unrifled) guns,especially in certain types of close range combat. Therefore, armingmechanisms driven by centrifugal force could not be used in ammunitionfor that type of gun.

The use of one or more shear pins, whose failure at the time of firingallowed a gear train mechanism to begin its cycle of operation, also hasleft much to be desired. These pins sometimes have failed to shear off,or have been found to shear off in such a way as to prohibit or retardproper operation of the gear train mechanisms with attendant ineffectiveresults.

Prior art bore riding pins used in arming mechanisms effected release ofthe mechanisms gear train by moving radially outward as soon as themissile passed from the gun barrel. However, no attempt was made tolimit the outward movement of these pins. Consequently, they flew offinto space in random paths, and presented a hazard to personnel andequipment in the vicinity.

We have eliminated the undesirable features of prior art armingmechanisms by providing one composed of comparatively few, easilymanufactured and assembled components. At the same time, as will becomeevident, we

have introduced to the art beneficial concepts fore known.

In essence, our arming mechanism, which is applicable to missiles firedfrom either smooth bore or from rifled bore guns, comprises anelectrically initiated detonator, a safety disc, and a booster powdercharge. The detonator and the booster powder charge are separated fromeach other by the safety disc which is rotatable between them. Thesafety disc is constantly urged to rotate so as to move a fire holecontained therein into coincidence with the detonator and the booster,making ignition of the booster possible as a result of ignition of thedetonator. Until the fire hole does move into coincidence with thedetonator and the booster, ignition of the booster charge, and in turnthe missiles main explosive charge, is prevented because the discs firehole provides the only means of passage between the detonator and thebooster. Rotation of the safety disc to allow ignition of the booster isprevented from occurring until after the missile equipped with ourmechanism has been discharged from the gun and has traveled a selecteddistance therefrom. Therefore, by restraining rotation of the safetydisc until after the ammunition has been fired, it is impossible todetonate the booster, even if the detonator should accidently beignited.

After the missile equipped with our arming mechanism has been fired andhas traveled a selected distance from the gun, the safety disc is causedto rotate so that its fire hole moves into alignment with the detonatorand the booster. Then, after the detonator is ignited in the usualmanner, fire from the detonator passes through the fire hole to ignitethe booster charge. Ignition of the booster charge then explodes theammunitions main powder charge.

One object of our invention is to simplify the design and to increasethe reliability of arming mechanisms by providing a rugged, dependablemechanism composed of comparatively few, easily manufactured andassembled com:

ponents.

Another object is to provide an arming mechanism which can be used withequal facility in smooth bore or in rifled bore guns.

A further object is to provide an arming mechanism in which the actionis not dependent upon shear pins.

A still further object is to provide an arming mechanism in which noparts fly ofi into space when the ammunition including the mechanismleaves the guns barrel.

The foregoing and other objects and advantages of our invention willbecome apparent from an inspection of the following description and theaccompanying drawings wherein: 1

Fig. 1 is a view of a representative firearm and contained ammunitionround, both partly broken away and partly in section to expose our novelarming mechanism;

Fig. 2 is a cross-section, partly broken away, taken along line 22 ofFig. l to show the appearance of the rear end (i.e., toward the firearmsbreech) of our safety mechanism; i

Fig. 3 is a cross-section taken along line 3-3 of Fig. 1 to show theinternal construction of our arming mechanism. Note that a boosterpowder charge, later shown in Figs. 3A, 4, and 5, is completelyinaccessible and does not appear in this drawing figure;

Fig. 3A is a cross-section similar to Fig. 3 but showing the mechanismat a later stage of operation such as happens after the ammunition isfired from the gun. Note especially that a safety disc within themechanism has been rotated (compare with Fig. 3) so that an openingtherein is in coincidence with the arming mechanisms booster powdercharge which, until now, had been covered by the safety disc. Thecomponents shown in this drawing figure, with the exception of thebooster powder charge, are common to Fig. 3, but some of the componotheretonents are in a different position as a result of the movementwhich has taken place. For brevity of drawing, a

portion of Fig. 3A hasbeen omitted but the parts removed.

have already been shown in Fig. 3;

Fig. 4 is a cross-section, partlybroken away, taken along line 4-4 ofFig. 1 and showing the appearance of the forward end (i.e., toward thefirearms muzzle) of our arming mechanism as well as more details ofinternal construction;

Fig. 5 is a cross-section taken along line 5-5 of Fig. 2 to show furtherstructural details; and

Fig. 6 is a cross-section taken along line 66 of Fig. 2 especially toshow the mechanisms release pin and the pins overload spring before themissile is fired.

For the purpose of explaining our inventive arming mechanism we haverepresented it as having been incorporated in the ammunition round for abazooka type gun. Those skilled in the art know that this ammunitionround is a type of rocket in that the whole round leaves the gun whenfired and carries the propellant with it along its trajectory.

The practical embodiment chosen to explain our invention has beenselected for illustrative purposes only and, therefore, it is not to beconstrued that our arming mechanism is applicable only to rocket typeammunition. Actually it can be incorporated with equal facility andeifectiveness into explosive projectiles of conventional ammunitionrounds in which the rounds cartridge case remains in the gun barrelafter firing.

As shown in Fig. 1, our arming mechanism 10 is illustrativelyincorporated in a rocket 11 which is shown in firing position within arepresentative launching tube 12. This rocket comprises the war head 13containing the main explosive charge 14 and a detonating mechanism (notshown), earlier mentioned arming mechanism 10 which is threaded-1yattached to the rear end 15 (i.e., toward the launching tubes breechend) of the war head, the adapter 16 which is threadedly attached to therear end of the arming mechanism, and the motor casing 17 which isthreadedly attached to the rear end of the adapter and which containsthe propellant 18.

In order to facilitate the comprehension of our novel arming mechanismand an appreciation of inventive concepts revealed therein, we shallfirst describe the components of which it is composed, then explain themode of its operation.

Body

The basic component of our arming mechanism is the cylindrical body 20(see Figs. 1 to 6). This body, as shown in Figs. 1 and 4 to 6, isprovided with a forward portion 21 (i.e., toward the muzzle of launchingtube 12) and, as shown in Figs. 1, 2, 5, and 6, with a rear portion 22(i.e., toward the launching tubes breech).

Forward portion 21 is of somewhat reduced diameter and is externallythreaded for attachment to the war heads rear end 15, as earliermentioned. As shown in Figs. 1 and 4 to 6, the diameter of cylindricalbody 20 is substantially the same as the diameter of the war heads rearend 15. Forward portion 21, moreover, is provided with an axial recess23 from the center of which projects a frangible lug 24 (see Figs. 4 and5).

The bodys rear portion 22 is reduced more in diameter than forwardportion 21, and is also externally threaded for attachment to theadapters muzzle end 25 (see Figs. 1, 2, 5, and 6). As shown in Figs. 1,5, and 6, the diameter of the adapters muzzle end is substantially thesame as the diameter of the body 20.

Extending axially into body 20 from rear portion 22 are a centrallylocated recess 26 (see Figs. 2, 5, and 6), a somewhat smallerdiametered, eccentrically located recess 27 (see Figs. 3 to 6), and astill smaller centrally located recess 28 (see Figs. 4 and 5).

Extending radially inward from the periphery of body 20 are theconcentric, stepped recesses 30, 31, and the opening 32 (see Figs. 3 to5). Recess 30 is the outermost and largest diametered member of thetrio, and is threaded. Recess 31 is located between recess 30 andopening 32, and is somewhat smaller in diameter than recess 30. Opening32 is the innermost and smallest in diameter of the three- As shown inFigs. 3 to 5, opening 32 enters eccentrically located recess 27 a shortdistance from the floor 33 of that recess, as best shown in Fig. 5.

Diametrically opposed to concentric, stepped recesses 30, 31, andopening 32, and also extending radially into body 26, are similarlydimensioned concentric, stepped recesses 35, 36, and an opening 37 (seeFigs. 3 and 5). From those figures it is apparent that the common axisof stepped recesses 35, 36, and opening 37 is substantially acontinuation of the common axis of stepped recesses 30, 31, and opening32. Like recess 30, recess 35 isthe outermost and largest diameteredmember of the trio, and is threaded. Recess 36, like recess 31, islocated between recess 35 and opening 37, and is somewhat smaller indiameter than recess 35. Opening 37, like opening 32, is the innermostand smallest in diameter of those three. As shown in Figs. 3 and 5,opening 37 enters eccentrically located recess 27 a short distance fromthe floor 33 of that recess as does earlier mentioned opening 32 (seeFig. 5).

Also extending radially inward from the periphery of body 20 are theconcentric, stepped, chordal directed recesses 40, 41 and the chordaldirected opening 42 (see Figs. 3 and 3A). Recess 40 is the outermost andlargest diametered member of that trio, and is threaded. Recess 41 islocated intermediate recess -40 and opening 42, and is somewhat smallerin diameter than recess 40. Opening 42 is the innermost and smallest indiameter of these three, and, like openings 32 and 37 opens intoeccentric recess 27 just clear of floor 33 of that recess. As best shownin Figs. 3, 3A, and 4, the axis of the chordal directed recesses 441,41, and chordal directed opening 4'2 is located substantiallyperpendicular to the common axis through openings 32 and 37. Opening 42enters recess 27 so close to the entrance thereinto by opening 32 thatonly a small space exists in the wall of the recess which separates theopenings.

Safety disc Rotatably accommodated in the bodys eccentrically locatedrecess 27 is the safety disc 45 (see Figs. 2 to 6). As shown in Figs. 3,3A, and 5, this disc is provided with opposed chordal directed notches46 and 47 which are cut into the discs periphery and extend between thediscs flat faces, an axially extending fire opening 48 (see Figs. 3, 3A,and 4), a release pin opening 43 (see Figs. 3, 3A, and 6), and a springopening 50 (see Figs. 3 to 4). Fire opening 48 and release pin opening49 are spaced from each other, their centers being on a diametral lineof disc 45 parallel to notches 46 and 47.

Actually, fire hole 48 is displaced from the safety discs axis bysubstantially the same amount that the axis of the bodys eccentricallylocated recess 27 is displaced from the bodys axis, and notches 46 and47 are offset from the diametral line through the centers of fireopening 48 and release pin opening 49 by substantially the same amountthat the axis of concentric, stepped, recesses 40, 41 and opening 42 isoffset from the axis of body 20. Spring opening 50 extends through thesafety disc parallel to the discs axis and is conveniently located,preferably near the discs periphery.

As best shown in Fig. 5, safety disc 45 is somewhat greater in thicknessthan the diameter of openings 32. and 37. The same is true relative toopening 42.

In the operation of our inventive arming mechanism, safety disc 45 isrotatable from an unarmed position best shown in Figs. 3 and 4 to 6 toan armed position shown in Fig. 3A.

When the safety disc is in the unarmed position, the bodys centrallylocated recess 28 is completely covered by the safety disc; and, whenthat disc is in the armed position, the discs fire opening 48 is incoincidence with the bodys centrally located recess. The significance ofthese conditions will become more apparent later in the description.

Cover plate Accommodated in the bodys recess 26 is the circular coverplate 53 (see Figs. 2, 5, and 6) which is secured to the body by meansof screws 54 (see Figs. 2 to 6). Cut into the forward face (i.e., towardwar head 13) of this plate is circular groove 55 (see Figs. 5 and 6),and extending from the bottom of groove 55 to the rear face (i.e.,toward adapter 16) of the plate is an arcuate slot 56 (see Figs. 2 and6) which has a notch 57 at one end (see Fig. 2).

Projecting from the forward face of the cover plate is an eccentricallylocated lug 58 (see Figs. 5 and 6) which extends part way into the bodyseccentrically located recess 27 very close to safety disc 45. Projectingin an opposite direction from the rear face of the cover plate is theaxially located lug 59 (see Figs. 1, 2, and 5). Cover plate 53 is alsoprovided with a centrally located recess 60 which extends from lug 58almost through lug 59 (see Figs. 2 and 5). Extending from the bottom ofthis recess to the outside of lug 59 is the opening 61. Somewhat offsetfrom the axis of cover plate 53 is an opening 62 (see Figs. 2 and 6)which extends through the cover plate as shown in Fig. 6.

The components previously described are the major parts of our inventivearming mechanism. To these larger components are added various other,smaller components now to be described.

Bore riding pins, retaining rings, coil springs Slidably accommodated ineach of the bodys diametrically opposed recesses 31 and 36 is a boreriding pin 65 (see Figs. 1 and 3 to 5). Each pin comprises a mainportion 66 having a conveniently shaped rounded outer end 67, a flange68, and a shank 69. Respective flanges 68 are accommodated in the bodysrecesses 31 and 36, respective shanks 69 are accommodated in openings 32and 37, and main portion 66 of each pin is slidab-le in the centralopening 70 of a retaining ring 71 which is threadedly attached to body20 in the threaded recesses 30 and 35 (see Figs. 3 to 5). Fitting aroundshank 69 of each pin between flange 68 and the bottom of respectiverecesses 31 and 36 is the coil spring 72 (also see Figs. 3 to 5) whichacts constantly to urge each bore riding pin radially outward from body20. However, from the drawings, especially Fig. 3A, it is evident thatthe outward movement of each bore riding pin is limited by retainingring 71 against which flange 68 abuts.

In practice, the length of each shank 69 is such that, when the boreriding pins are depressed inside body 20, the inner end of each pinengages the safety discs notches 46 and 47, respectively, and therebyprevents the disc from being rotated; and, when the bore riding pins arepushed outward after leaving the gun barrel, the inner end of each pinis clear of the safety disc and thereby permits the disc to be turned.

After the assembly of our arming mechanism a band (not shown), whichholds the bore riding pins depressed in the same manner as they aredepressed when in the launching tube, or other gun (see Figs. 3, 4, and5) is placed around the rocket. Thus, safety disc 45 is secured againstrotation, in one respect, by means of the bore riding pins. Thisarrangement makes it impossible for war head 13 to be explodedprematurely. Later in the description we shall describe a second meansby which the safety disc is prevented from rotating until the propertime.

Detent, detent spring, plug Slidably accommodated in the bodys recess 41is the cylindrical detent 75 (see Figs. 3, 3A, and 4). This detentcomprises the head 76 and the shank 77 which are slidable in recess 41and opening .42, respectively. Threadedly secured in the bodys recess 40is the retaining plug 78 (also see Figs. 3, 3A, and 4). Between theretaining plug and the detents headis a coil spring 79 (see Figs. 3 to4) which acts constantly to depress detent 75. As will later be shown,this detent engages notch 47 during operation of our arming mechanism.

Torsion spring, release pin, overload spring, retaining spring Safetydisc 45 is constantly urged to rotate in a counterclockwise direction,as viewed in Fig. 3, by means of a torsion spring 80 (best shown inFigs. 5 and 6). The forward end 81 (i.e., toward war head 13) of thisspring is conveniently shaped for engagement with the safety discsopening 50 (see Figs. 3, 3A, and 4), and the rear end 82 of the spring(i.e., toward adapter 16) is likewise conveniently shaped to engage inthe arcuate slots notch 57 (see Fig. 2).

Rotation of the safety disc, however, is prevented by a cylindricalrelease pin 83 until after firing. This pin is slidably accommodatedpartly in the safety discs opening 49 and in the cover plates opening 62(see Figs. 2, 3, and 6). This restraint is in addition to, andindependent of, that provided by the earlier mentioned bore riding pins65 when they are depressed into body 20.

Release pin 83 is retained in place until firing of rocket 11 by meansof an overload spring 84 (see Figs. 2, 5, and 6) which is held in placeon cover plate 53 by means of one of the screws 54 which holds the coverplate to body 20 (see Figs. 2 and 6). As shown in the drawings, overloadspring is a leaf spring, one end of which covers part of the coverplates opening 62 and thereby interferes with the movement of releasepin 83 past that point.

Overload spring 84 is carefully calibrated so as to exert only a certainamount of force against release pin 83.

Actually, this force is such as readily to be overcome by its own andthe release pins inertia when the rocket is fired, so that the releasepin moves backward (i.e., toward adapter 16) out of engagement with thesafety discs opening 49'. The disengagement between release pin 83 andsafety disc 45 will allow the safety disc to be rotated after therestraint afforded by bore riding pins 65 is removed.

In order to make certain that the rear end 82 of the torsion springwhich is in notch 5-7 cannot escape from that end of slot 56 and therebylose its tendency to rotate the safety disc, a uniplanar retainingspring 85 is placed across arcuate slot 56 (see Fig. 2). As there shown,one end of this spring is secured to cover plate 53 by screw 54, whichalso binds the cover plate to body 20, and the other end of the springpartly encricles the cover plates lug 59. Thus, if for some reasonspring end 8 2 should become dislodged from notch 57, it cannot escapepast retaining spring 85 and thereby become unwound.

Detonator and booster charge To complete the components of our armingmechanism, we have provided an electric detonator 86 (see Figs. 2 and 5)and a booster charge 87 (see Figs. 3A, 4, and 5).

The electric detonator, having the leads 88 and 89, is accommodated inthe cover plates central recess 60. The detonators leads extend towardadapter 16 through opening 61 (see Fig. 5), then change direction (seeFig. 1) and extend through an opening 90 in the cover plate (see Fig. 2)and an opening 91 in body 20 (see Figs. 3 and 4) toward war head 13where they are attached, in well-known manner, to any conventionalelectrical detonating mechanism (not shown). Although many suchdetonating devices are well known, an example of one may be found inco-pending application, Serial No. 141,802, now Patent No. 2,800,081,filed on February 1, 1950 by W. J. Kroeger and G. E. Hirt for CombinedElectromagnetic Fuze and Electric Detonator. The

underlying principle of such mechanisms typically involves the use of awire coil which encircles a reciprocating magnet, this apparatusgenerating electrical power when the projectile in which it is mountedstrikes a target and causes rapid relative movement between the magnetand coil.

Booster charge 87 is accommodated in the bodys recess 28. This charge(as shown in Fig. is separated from the detonator by the safety discwhen that disc is in the unarmed position. As will later be shown, whenthe safety disc is in the armed position, the safety discs fire opening48 will lie between the detonator and the booster so that fire from thedetonator can pass directly to the booster.

Operation of arming mechanism Having presented and described thecomponents incorporated in our inventive arming mechanism, its operationin the illustrative practical application to a rocket will now beexplained. Previously we pointed out how, by virtue of the fact that thesafety disc in our novel device acts as a barrier between the electricdetonator and the booster charge, it is impossible accidentally todetonate the war head of a rocket, or an explosive projectile of aconventional round, in which our device is incorporated. Now we shallexplain how the thus equipped rocket, or other missile is made capableof exploding upon firing.

The rocket incorporating our arming mechanism is thrust into launchingtube 12 (see Fig. 1). In inserting the rocket the storage ring (notshown), which was put circumferentially around the rocket at assembly tohold bore riding pins 65 depressed before use, is stripped off therocket by the launching tubes inside diameter which is substantially thesame as the inside diameter of the storage ring. As soon as the boreriding pins are inside the launching tube, they are depressed by thetube so that their inner ends engage the safety discs notches 46 and 47(see Figs. 3, 4, and 5). In other words, the rocket is unarmed becausethe safety disc is fixed in position to act as a barrier between thedetonator and the explosive charge.

When the gun is fired, the inertia of release pin 83 overcomes therestraint imposed upon it by overload spring 84 and the pin becomesdisengaged from the safety disc. However, as long as the rocket is inthe barrel of the gun, bore riding pins 65 remain depressed, therebypreventing rotation of safety disc 45 and thus maintaining the rocket inthe unarmed condition.

As soon as the rocket leaves the guns barrel, the bore riding pins areforced fully outwardly by springs 72 tmtil the pins flanges 6% abutretaining rings 71. At that time, the pins inner ends are clear of thesafety disc, and torsion spring 86 acts to rotate the disc until thediscs fire opening 48 is in coincidence with detonator 86 and boostercharge 87. Thus the rocket becomes armed. When this alignment isestablished, notch 47 is in alignment with detent 75 which is promptlyurged into that notch by spring 79, thereby locking the safety disc inthe armed position.

When the rocket strikes its target (not shown) electricity is generatedin well known manner, as was previously explained. This electricitytravels through leads 88 and 89' to heat detonator 86 to the ignitionpoint. Fire from this detonator then passes through fire hole 48 toignite booster charge 87. Energy from this action blows frangible lug2.4- apart and ignites main explosive charge 14.

The rate of rotation of safety disc 45 from the unarmed to the armedposition can be controlled, depending upon the pressure exerted againstthe safety disc by detent 75 which acts as a brake on the safety discand also by the calibration of torsion spring 80. In this manner it ispossible to adjust the time and distance from the launching tube untilthe rocket becomes armed.

From the foregoing it will be apparent that we have simplified thedesign and increased the reliability of arming mechanisms by providing arugged, dependable mechanism composed of comparatively few, easilymanufactured and assembled components; that we have provided an armingmechanism which can be used with equal facility in smooth bore or inrifled bore guns; that we have provided an arming mechanism in which theaction is not dependent upon shear pins; and, that we have provided anarming mechanism in which no parts fly off into space when theammunition including the mechanism leaves the guns barrel.

Those skilled in the art will realize that our arming mechanism isadaptable to numerous variations and modifications without departingfrom its original spirit and scope. For that reason, we do not wish tobe limited in patent coverage to the narrow limits inherent in theparticular embodiment here disclosed for illustrative reasons only, butrather only by the breadth and scope of the appended claims.

We claim:

1. A safety arming device for an explosive missile comprising, a body, acover plate attached to said body, an explosive charge in said body, adetonator located in said cover plate, a safety disc rotatably mountedin said body so that when in its unarmed position a portion of the disccan selectively separate said explosive charge and said detonator butupon rotation to its armed position another disc portion having anopening therethrough can provide a communicating passageway between saidexplosive charge and said detonator, a release pin slidably accommodatedin said cover plate and in said safety disc for securing the safety discagainst rotation, an overload spring for holding said release pin inposition to bar rotation of the safety disc until the explosive missilehas been fired and thus given a predetermined minimum forward thrust, abore riding pin movably mounted in a recess in said body and adaptedwhen depressed into the bodys recess to engage said safety disc so as toprevent rotation thereof but when sufliciently expressed from the bodysrecess to become disengaged from the safety disc to allow the discsrotation, a coil spring constantly tending to express said bore ridingpin from said bodys recess, a retaining ring in said bodys recess forlimiting the outward movement of said bore riding pin from said body soas to prevent the pins separation from the body after the missile leavesthe gun from which it is fired, a torque spring for rotating said safetydisc from the unarmed to the armed position after said release pin andsaid bore riding pin are disengaged from said safety disc, a detentfrictionally operable as a brake on said safety disc to control thespeed of the discs rotation from the unarmed to the armed position andalso operable to lock the disc in the armed position, and meansconstantly urging said detent toward said rotating disc with apreselected braking force, whereby said safety device prevents arming ofthe explosive missile until after it has been tired from the gun and hastraveled a predetermined minimum distance therefrom and then positivelymaintains the armed condition of the missile while in flight.

2. The combination, in a safety arming device for an explosive missilecomprising, a body, a cover plate attached to said body, an explosivecharge in said body, a detonator located in said cover plate, a safetydisc rotatably mounted in said body so that when in its unarmed positiona portion of the disc can selectively separate said explosive charge andsaid detonator but upon rotation to its armed position another discportion having an opening therethrough can provide a communicatingpassageway between said explosive charge and said detonator, a releasepin slidably accommodated in said cover plate and in said safety discfor securing the safety disc against rotation, an overload spring forholding said release pin in position to bar rotation of the safety discuntil the explosive missile has been fired and thus given apredetermined forward thrust, a bore riding pin movably mounted in arecess in said body and having a flange, said bore riding pin beingadapted when depressed into said bodys recess to engage said safety discso as to prevent rotation thereof but when sufliciently expressed fromthe bodys recess to become disengaged from the safety disc to allow thediscs rotation, 21 first coil spring constantly tending to express saidbore riding pin from said body, a retaining ring filling a portion ofsaid bodys recess for preventing movement therepast of said bore ridingpins flange and thereby preventing the pins separation from the bodyafter the missile leaves the gun from which it is fired, a torque springfor rotating said safety disc from the unarmed to the armed positionafter said release pin and said bore riding pin are disengaged from saidsafety disc, a detent frictionally operable as a brake on said safetydiscs circumferential surface to control the speed of the discs rotationfrom the unarmed to the armed position and also operable to lock thedisc in the armed position, said detent being movable in a directionsubstantially perpendicular to the 1,547,599 Lukens July 28, 19251,561,687 Brayton Nov. 17, 1925 2,030,085 Woodberry Feb. 11, 19362,118,062 Woodberry May 24, 1943 2,336,514 Teitscheid Dec. 14, 1943FOREIGN PATENTS 257,335 Great Britain Aug. 27, 1926

